PRELIMINARY STUDIES ON PHYSIOLOGICAL CHANGES AND INJURY MECHANISM IN AQUATIC VASCULAR PLANTS TREATED WITH CADMIUM
SUN SAI-CHU, WANG HUAN-XIAo AND LI QI-REN(Yunnan University)
The results of the study on aquatic vascular plants under cadmium (Cd~(++)) pollution show that there is a significant negative correlation between chlorophyll content and Cd~(++) concentration but a strong positive correlation between permeability of cell membrane in the leaf, as judged by exosmosis, and Cd~(++) concentration. Soluble sugars in the leaves of the various species tested increased with the increase of Cd~(++) concentration though the rate of increase is much slower in the resistance species. The activity of dehydrogenase extracted from the root was inhibited by Cd~(++), the inhibition being more pronounced as Cd~(++) concentration increased. Changes in peroxidase isozyme pattern in the plant species studied were related to the Cd~(++) concentration used. The changes reported are useful and effective indices in monitoring the environment. Gel filtration of the soluble fraction shows that in Eichhornia crassipes, a resistant species, Cd~(++) is associated with high molecular weight components (mol wt70,000 D,) a 13,300 D component, and low molecular weight chelators, and free Cd~(++), while in Spirodela polyrhiza, a non-resistant species, the 13,300 D Cd complex is not found.